i had to recently change my 12V battery, but couldn’t find the location of the battery, so I went to a workshop instead. They could not find the battery either, so I dug deeper online and finally found it! There’s a PDF in German that shows the location PDF Its in the trunk, behind many bolts and a cooling system that has to be unscrewed and moved a bit aside. The location is doable but requires some patience and more time than my previous cars, but it is swappable without having to go to a shop. After swapping, the new battery needs to be programmed using some OBD tool, which can be done with tools that you can buy, but also a lot of electronic failure faults show up, which required the workshop to use some bigger OBD tool to clear up. If those tools like OBD11 can clear the faults then everything can be DIY.
skoda-octavia-iv-phev-hybrid-baujahr-ab-2020.pdf